Miniature optical zoom lens

ABSTRACT

Miniature zoom lens systems and methods of manufacturing thereof are described. An exemplary system includes a first prism positioned to receive incident light from an entrance to the miniature lens system, at least a first varifocal lens positioned to receive the light that exits the prism, at least one base lens positioned to receive the light after passing through the first varifocal lens, a detector positioned to receive the light after passing through the base lens, and a first actuator configured to move the first varifocal lens in at least a direction perpendicular to propagation axis of the light passing through the first varifocal lens. The miniature lens system has a small z-height and can be implemented in mobile devices such as mobile phones.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of PCT Application No.PCT/IB2013/002905, entitled “MINIATURE OPTICAL ZOOM LENS”, filed on Nov.8, 2013, which in turn is a PCT conversion of U.S. Provisional PatentApplication No. 61/724,221, entitled “INTEGRATED ELASTIC SUSPENSIONPLATFORM WITH OPTICAL COMPONENTS” filed on Nov. 8, 2012, and also ofU.S. Provisional Patent Application No. 61/874,333, entitled “MINIATUREOPTICAL ZOOM LENS” filed on Sep. 5, 2013. This application is further acontinuation-in-part of PCT Application No. PCT/IB2015/000409, entitled‘LENS ASSEMBLIES AND ACTUATORS FOR OPTICAL SYSTEMS AND METHODSTHEREFOR”, filed on Jan. 8, 2015, which in turn is a conversion of U.S.Provisional Patent Application No. 61/925,215, filed on Jan. 8, 2014,Each of the foregoing applications is incorporated herein by reference,and the present application claims the benefit of priority from each ofthe foregoing.

BACKGROUND

The present disclosure relates to optical systems and methods ofmanufacturing thereof and more particularly to zoom lens systems andmethods of manufacturing.

The alignment of components in an optical system is an important factorin achieving optimal system performance and a desired image quality.Proliferation of small-scale optical systems for use in, for example, avariety of handheld devices, such as cell phones and hand-held cameras,places additional challenges on alignment tolerances due to the smalldimensions of optical components within such devices. As such, thereexists a need to improve the alignment of components in an opticalsystem in order to achieve optimal performance while minimizing thesystem's overall form factor. Further, it is essential to minimize thesize of the optical systems that are used in, for example, consumerdevices, such as phones and hand-held cameras.

SUMMARY

The disclosed embodiments relate to systems and methods for improvingthe alignment of optical components within an optical systems. Thedisclosed embodiments further relate to miniature zoom lens systems andmethods for their manufacture and assembly that allow the production ofsmall lens systems in a streamlined fashion. In some exemplaryembodiments, the disclosed embodiments are used to align varifocallenses of an optical system to decrease the overall size of the systemwhile optimizing its performance.

In systems with moving optical components, such as zoom lens systems,alignment of optical components is complicated due to their mobility. Insome systems, optical components are moved only along the optical axis(i.e., along the z-axis), which makes alignment along the optical axisparticularly important. Alternatively, or additionally, in some systems,such as in an Alvarez lens configuration, optical components can moveperpendicular to the optical axis, which makes proper alignment of theelements in multiple dimensions even more challenging. Alignment issuescan be further exacerbated in systems where components with aspheric orfree-form surfaces are used since such components may not have an axisof symmetry.

The disclosed embodiments seek to provide methods and system forproperly aligning optical components by moving them both along andperpendicular to the z-axis (i.e., the optical axis) in order tominimize the length of the optical path while maintaining the quality ofimages captured by such optical systems. By using freeform lenses, suchas Alvarez lenses, it is possible to achieve optimal focusing andzooming of an image within a diminutive amount of space by actuatinglenses at right angles to the z-axis in addition to moving the lensesand other optical components along the z-axis.

This reduction in the optical path's length enables a reduction in theoverall size of the optical system, since less space would be requiredto carry an image through the system's lenses. As such, optimizedalignment of the lens elements in a miniature optical system inaccordance with the disclosed embodiments leads to smaller opticalsystems in devices that use such systems, such as cell phones anddigital cameras. This reduction in optical system size allows suchdevices to have more room for other components, such as batteries andprocessors, or allows them to achieve an overall reduction in sizealtogether. As these devices become smaller and smaller, the need forsuch miniaturization of key technological components will be paramountto maintaining a competitive edge for those companies that manufactureand sell such devices.

One aspect of the disclosed embodiments relates to an integrated opticaldevice that includes an elastic suspension fixture fabricated using afirst process, and an optical element integrated into the elasticsuspension fixture. The optical element is fabricated using a secondprocess. In one exemplary embodiment, the first process comprises one ofthe following processes: an injection molding process, an in-molddecoration process, a hot stamping process, a metal stamping process, amicro-fabrication process that produces a chip-based mold, or an insertmolding process. In another exemplary embodiment, the second processcomprises one of the following processes: an injection molding process,a casting from a mold process, an in-mold decoration process, a hotstamping process, a metal stamping process, a micro-fabrication processthat produces a chip-based mold, or an insert molding process.

According to one exemplary embodiment, the integrated optical devicefurther includes one or more of the following: a frame, one or morealignment structures, an actuator configured to displace the opticalelement, one or more additional optical elements, one or more additionalelastic elements, and one or more rigid elements. In yet anotherexemplary embodiment, the elastic fixture is configured to allowmovement of the optical element in one or more directions. In stillanother exemplary embodiment, the elastic fixture is configured to allowmovement of the optical element in three dimensions.

In one exemplary embodiment, the integrated optical device furtherincludes an actuator configured to displace the elastic feature and tothereby displace the optical element. In another exemplary embodiment,the optical element comprises at least one of the following surfaces: aspheric surface, an aspheric surface, or a free-form surface.

Another aspect of the disclosed embodiments relates to a zoom lens thatincludes the above noted integrated optical device. Yet another aspectof the disclosed embodiments relates to a handheld electronic devicecomprising the above noted integrated optical device.

In another embodiment, the optical element and frame structure is moldedin a single step. Alignment of the optical element is controlled throughthe molding process and one less assembly step is needed. The lenselement and frame structure is then made of the same material. Thematerial of choice is a balance of fulfilling optical requirements suchas refractive index for the lens element and mechanical requirementssuch as yield strength for the frame. Typical materials for polymersinclude but are not limited to Zeonex and polycarbonates.

Additional post-processing steps can be performed to address therequirements. For example, diamond-like coating can be coated on theintegrated structure on the non-optical portions to increase structuralstrength as well as reduce friction. An opaque coating can be used toreduce light transmission through the integrated lens structure otherthan the active lens element area.

Another aspect of the disclosed embodiments relates to a method forfabricating an integrated optical device, that includes obtaining afirst mold that is structured to form an elastic suspension fixture,injecting a first injection material into the first mold, and placing asecond mold in contact with the first mold and the first injectionmaterial within the first mold, where the second mold is structured toform an optical element. The method also includes injecting a secondinjection material into the second mold, removing the second mold, andremoving the first mold to obtain the elastic suspension fixture withthe optical element integrated thereto

In one exemplary embodiment, the first injection material comprises afirst polymer suitable for formation of the elastic suspension fixture,and the second injection material comprises a polymer suitable forformation of the optical element. In another exemplary embodiment, themethod further includes further refining structure of the integratedoptical device using a precision machining tool. In still anotherexemplary embodiment, the method further includes, prior to removing thefirst mold, placing a third mold in contact with the first mold and thefirst injection material, where the third mold is structured to form anadditional element, and injecting a third injection material into thethird mold.

According to another exemplary embodiment, the additional element is oneof: an additional optical element, an additional elastic fixture; or arigid fixture. In one exemplary embodiment, the additional element is analignment fixture. In yet another exemplary embodiment, componentswithin the integrated optical devices are positioned according to atolerance in the range of 1 to 5 microns. In another exemplaryembodiment, the third injection material is the same material as one ofthe first injection material and the second injection material.

In one exemplary embodiment, the first mold is additionally structuredto comprise a groove for placement of an actuation mechanism. In anotherexemplary embodiment, the above method further includes integrating ametallic frame into the elastic suspension fixture. In another exemplaryembodiment, the metallic frame is formed using a metal stampingtechnique.

Another aspect of the disclosed embodiments relates to a method forfabricating an integrated optical device that includes obtaining a firstmold that is structured to form an elastic suspension fixture and anoptical element, injecting a first injection material into the firstmold, injecting a second injection material into the first mold, andremoving the first mold to obtain the elastic suspension fixture withthe optical element integrated thereto.

Another aspect of the disclosed embodiments relates to a method forfabricating an integrated optical device that includes obtaining a moldthat is structured to form an elastic suspension fixture and to house anoptical element, placing the optical element in the mold, injecting afirst injection material into the mold to form an elastic suspensionfixture, and removing the mold to obtain the elastic suspension fixturewith the optical element integrated thereto. In one exemplaryembodiment, the optical element is cast from a mold prior to placing theoptical element in the mold.

Another aspect of the disclosed embodiments relates to a miniature zoomlens system that includes a first prism positioned to receive incidentlight from an entrance to the miniature lens system through a first faceof the first prism and to bend the received light by approximately 90degrees before allowing the light to exit from a second face of thefirst prism, and at least a first varifocal lens positioned to receivethe light that exits the second face of the prism. The miniature zoomlens system further includes at least one base lens positioned toreceive the light after passing through the first varifocal lens, adetector positioned to receive the light after passing through the baselens, and a first actuator configured to move the first varifocal lensin at least a direction perpendicular to propagation axis of the lightpassing through the first varifocal lens.

In one exemplary embodiment, at least one face of the first prism has afreeform surface. In another exemplary embodiment, the first varifocallens is one of the following: a liquid crystal lens, a liquid lens, oran Alvarez-like lens. In another exemplary embodiment, the detectorcomprises a complementary metal-oxide semiconductor (CMOS). In yetanother exemplary embodiment, the first actuator comprises one of a coilor a magnet. In still another exemplary embodiment, the above miniaturezoom lens system includes a structural platform to allow one of thefollowing to be directly molded onto, fabricated onto, or integratedwith the structural platform: the first prism, a second prism, the firstvarifocal lens, or a second varifocal lens. In one exemplary embodiment,the structural platform comprises a spring flexure element. In anotherexemplary embodiment, thee structural platform includes a frame and anarm.

According to another exemplary embodiment, the structural platform framecomprises a lead frame metal structure that is one or more of: ametal-stamped structure, a laser-cut structure, a milled structure, anetched structure, or a molded structure. In such an exemplaryembodiment, the arm is molded on the lead frame structure, and one ormore of the first prism, a second prism, the first varifocal lens, or asecond varifocal lens is molded onto the lead frame.

In one exemplary embodiment, a wafer-level optical component with apreformed lens element is bonded to the platform. In another exemplaryembodiment, the first actuator is a voice-coil actuator with abidirectional drive. In yet another exemplary embodiment, the miniaturezoom lens system also includes a second actuator configured to move anoptical component other than the first varifocal lens within theminiature zoom lens system. In still another exemplary embodiment, thesecond actuator and the first actuator are configured to displace boththe optical component other than the first varifocal lens and the firstvarifocal lens by the same distance and in the same direction. In oneexemplary embodiment, the optical component other than the firstvarifocal lens is one of: a second varifocal lens, the at least one baselens, the first prism, or a second prism.

According to another exemplary embodiment, the first varifocal lens hasa rectangular or an oval-shaped cross section encompassing only anessential active area of the first varifocal lens. In another exemplaryembodiment, the miniature zoom lens system further includes a secondvarifocal lens positioned to receive the light exiting the firstvarifocal lens before reaching the at least one base lens. In stillanother exemplary embodiment, the second varifocal lens has arectangular or an oval-shaped cross section encompassing only anessential active area of the second varifocal lens. In yet anotherexemplary embodiment, both the first and the second varifocal lenses aremovable with respect to one another so as to provide optical zoomcapability for the lens system.

In one exemplary embodiment, the at least one base lens is configured tomove along optical axis of the base lens so as to provide opticalfocusing ability for the lens system through only movement of the baselens. In another exemplary embodiment, one or more of the firstvarifocal lens, the second varifocal lens or the at least one base lensis a liquid lens, a liquid crystal lens, a MEMS-based lens, anAlvarez-like lens, a piezo-based lens, or a combination thereof. Inanother exemplary embodiment, the spring flexure is one of a simple beamflexure or a cascaded beam flexure.

An embodiment includes a first varifocal lens positioned to receive theincident light from an entrance to the miniature lens system, a firstprism positioned to receive the light that exits the first varifocallens through a first face of the first prism and to bend the lightreceived by the first prism by approximately 90 degrees before allowingthe light to exit from a second face of the first prism, and a fixedlens or lens group is positioned to receive the light that exits thefirst prism.

A second varifocal lens is positioned after the lens or lens group. Atleast one base lens positioned to receive the light after passingthrough the second varifocal lens, a second prism may or may not benecessarily positioned to receive the light that exits the at least onebase lens through a first face of the second prism and to bend the lightby approximated 90 degrees before allowing the light to exit from asecond face of the second prism, a detector positioned to receive thelight after exiting the second prism, and at least one actuatorconfigured to move one or both of the first varifocal lenses in at leasta direction perpendicular to propagation axis of the light passingthrough the first of the second varifocal lenses. The second prismserves to position the detector in a smaller configuration such that thez-axis height of the module can be minimized. The material selection ofthe second prism also serves to correct for chromatic aberration in theimage.

With the fixed lens or lens group after the first prism, the opticalpower of the varifocal lenses can be reduced. The reduction in opticalpower helps in the profile gradient of the varifocal lenses, resultingin better manufacturability. The material of the fixed lens or lensgroup can also be chosen to help in correcting chromatic aberrationswhich is a key aberration for zoom lenses.

Another embodiment includes a first varifocal lens positioned to receivethe incident light from an entrance to the miniature lens system, afirst prism positioned to receive the light that exits the firstvarifocal lens through a first face of the first prism and to bend thelight received by the first prism by approximately 90 degrees beforeallowing the light to exit from a second face of the first prism, afixed freeform lens is positioned to receive the light that exits thefirst prism.

A second varifocal lens is positioned after the fixed freeform lens. Atleast one base lens positioned to receive the light after passingthrough the second varifocal lens, a second prism may or may not benecessarily positioned to receive the light that exits the at least onebase lens through a first face of the second prism and to bend the lightby approximated 90 degrees before allowing the light to exit from asecond face of the second prism, a detector positioned to receive thelight after exiting the second prism, and at least one actuatorconfigured to move one or both of the first varifocal lenses in at leasta direction perpendicular to propagation axis of the light passingthrough the first of the second varifocal lenses. The second prismserves to position the detector in a smaller configuration such that thez-axis height of the module can be minimized. The material selection ofthe second prism also serves to correct for chromatic aberration in theimage.

The fixed freeform lens serves to reduce the optical power of thevarifocal lenses. The additional freedom that a freeform lens providesadditional tools to correct for other aberrations in the optical system.For example, correcting distortions and other asymmetries in the beamprofile due to the varifocal lenses. The material of the freeform lenscan also be chosen to help in correcting chromatic aberrations which isa key aberration for zoom lenses.

Another embodiment includes a first varifocal lens positioned to receivethe incident light from an entrance to the miniature lens system, afirst prism positioned to receive the light that exits the firstvarifocal lens through a first face of the first prism and to bend thelight received by the first prism by approximately 90 degrees beforeallowing the light to exit from a second face of the first prism, asecond varifocal lens is positioned after prism.

The second varifocal lens is an Alvarez-lens pair with an additionalfreeform lens moving in tandem with one of the lenses in theAlvarez-lens pair. This allows the gradient of the profile in theAlvarez-lens group to be reduced for ease of manufacturability. Theadditional freedom in the lens profile helps to correct for asymmetry inthe aberrations.

At least one base lens positioned to receive the light after passingthrough the second varifocal lens, a second prism may or may not benecessarily positioned to receive the light that exits the at least onebase lens through a first face of the second prism and to bend the lightby approximated 90 degrees before allowing the light to exit from asecond face of the second prism, a detector positioned to receive thelight after exiting the second prism, and at least one actuatorconfigured to move one or both of the first varifocal lenses in at leasta direction perpendicular to propagation axis of the light passingthrough the first of the second varifocal lenses. The second prismserves to position the detector in a smaller configuration such that thez-axis height of the module can be minimized. The material selection ofthe second prism also serves to correct for chromatic aberration in theimage.

An embodiment includes a first varifocal lens positioned to receive theincident light from an entrance to the miniature lens system, a firstprism positioned to receive the light that exits the first varifocallens through a first face of the first prism and to bend the lightreceived by the first prism by approximately 90 degrees before allowingthe light to exit from a second face of the first prism.

A second varifocal lens is positioned after first prism. At least onebase lens positioned to receive the light after passing through thesecond varifocal lens. A freeform lens is placed together with the baselens for additional aberration correction.

A second prism may or may not be necessarily positioned to receive thelight that exits the at least one base lens through a first face of thesecond prism and to bend the light by approximated 90 degrees beforeallowing the light to exit from a second face of the second prism, adetector positioned to receive the light after exiting the second prism,and at least one actuator configured to move one or both of the firstvarifocal lenses in at least a direction perpendicular to propagationaxis of the light passing through the first of the second varifocallenses. The second prism serves to position the detector in a smallerconfiguration such that the z-axis height of the module can beminimized. The material selection of the second prism also serves tocorrect for chromatic aberration in the image.

An embodiment includes a first varifocal lens positioned to receive theincident light from an entrance to the miniature lens system, a firstprism positioned to receive the light that exits the first varifocallens through a first face of the first prism and to bend the lightreceived by the first prism by approximately 90 degrees before allowingthe light to exit from a second face of the first prism.

A second varifocal lens is positioned after first prism. At least twobase lens which serves as a lens group is positioned to receive thelight after passing through the second varifocal lens. Of the at leasttwo base lens, at least one of them is fixed, the other base lenses aremovable, changing the optical power of the base lens group. The variableoptical power aids in the focusing of the image as well as reducing theoptical power change the varifocal lenses has to undertake to performzoom. That helps in manufacturability of the profiles of the lenses oran increase to the overall optical power change the whole optical systemcan undertake.

A second prism may or may not be necessarily positioned to receive thelight that exits the at least one base lens through a first face of thesecond prism and to bend the light by approximated 90 degrees beforeallowing the light to exit from a second face of the second prism, adetector positioned to receive the light after exiting the second prism,and at least one actuator configured to move one or both of the firstvarifocal lenses in at least a direction perpendicular to propagationaxis of the light passing through the first of the second varifocallenses. The second prism serves to position the detector in a smallerconfiguration such that the z-axis height of the module can beminimized. The material selection of the second prism also serves tocorrect for chromatic aberration in the image.

Another aspect of the disclosed embodiments relates to a miniature zoomlens system that includes a first prism positioned to receive incidentlight from an entrance to the miniature lens system through a first faceof the first prism and to bend the received light by approximately 90degrees before allowing the light to exit from a second face of thefirst prism, and a first varifocal lens positioned to receive the lightthat exits the second face of the prism. Such a miniature zoom lenssystem also includes a second varifocal lens positioned to receive thelight that exits first varifocal lens, at least one base lens positionedto receive the light after passing through the second varifocal lens, asecond prism positioned to receive the light that exits the at least onebase lens through a first face of the second prism and to bend the lightreceived by the second prism by approximately 90 degrees before allowingthe light to exit from a second face of the second prism, a detectorpositioned to receive the light after exiting the second prism, and atleast one actuator configured to move one or both of the first varifocaland second varifocal lenses in at least a direction perpendicular topropagation axis of the light passing through the first or the secondvarifocal lenses.

Another aspect of the disclosed embodiments relates to a miniature zoomlens system that includes a first varifocal lens positioned to receivethe incident light from an entrance to the miniature lens system, afirst prism positioned to receive the light that exits the firstvarifocal lens through a first face of the first prism and to bend thelight received by the first prism by approximately 90 degrees beforeallowing the light to exit from a second face of the first prism, asecond varifocal lens positioned to receive the light that exits firstprism, at least one base lens positioned to receive the light afterpassing through the second varifocal lens, a second prism positioned toreceive the light that exits the at least one base lens through a firstface of the second prism and to bend the light received by the secondprism by approximately 90 degrees before allowing the light to exit froma second face of the second prism, a detector positioned to receive thelight after exiting the second prism, and at least one actuatorconfigured to move one or both of the first varifocal and secondvarifocal lenses in at least a direction perpendicular to propagationaxis of the light passing through the first or the second varifocallenses.

In one exemplary embodiment, the second prism is orientated such as toallow placement of the detector on the same side of the miniature zoomlens system as the entrance to the miniature zoom lens system. Inanother exemplary embodiment, the second prism is orientated such as toallow placement of the detector on a side of the miniature zoom lenssystem that is opposite to the entrance to the miniature zoom lenssystem.

Another aspect of the disclose embodiments relates to a miniature zoomlens system that includes a first varifocal lens positioned to receivethe incident light from an entrance to the miniature lens system, afirst prism positioned to receive the light that exits the firstvarifocal lens through a first face of the first prism and to bend thelight received by the first prism by approximately 90 degrees beforeallowing the light to exit from a second face of the first prism, asecond varifocal lens positioned to receive the light that exits firstprism, at least one base lens positioned to receive the light afterpassing through the second varifocal lens, a detector positioned alongthe optical axis of the at least one base lens to receive the lightafter exiting the at least one base lens, and at least one actuatorconfigured to move one or both of the first varifocal and secondvarifocal lenses in at least a direction perpendicular to propagationaxis of the light passing through the first or the second varifocallenses.

In one exemplary embodiment, the first varifocal lens and the firstprism are formed as an integrated structure thereby reducing opticalpath length of light propagating through the miniature lens system. Inanother exemplary embodiment, one or more optical elements of the firstvarifocal lens are positioned to configure the first varifocal lens as alens with a negative optical power, and one or more optical elements ofthe second varifocal lens are positioned to configure the secondvarifocal lens as a lens with a positive optical power.

In yet another exemplary embodiment, one or more optical elements of thefirst varifocal lens are positioned to configure the first varifocallens as a lens with a positive optical power, and one or more opticalelements of the second varifocal lens are positioned to configure thesecond varifocal lens as a lens with a negative optical power. In stillanother exemplary embodiment, one or more optical elements of the firstvarifocal lens are movable so as to allow an optical power of the firstvarifocal lens to change in response to the movement of the one or moreoptical elements of the first varifocal lens. In one exemplaryembodiment, one or more optical elements of the second varifocal lensare movable so as to allow an optical power of the second varifocal lensto change in response to the movement of the one or more opticalelements of the first varifocal lens.

Another aspect of the disclosed embodiments relates to an Alvarez lensconfiguration that includes a first optical element and a second opticalelement, where each optical element includes two surfaces that aresubstantially perpendicular to an optical axis of the lensconfiguration, and a first surface of each the optical elements is aplane surface and a second surface of each of the optical elements is asurface characterized by a polynomial. Alternatively, both surfaces ofeither or both of the first and second optical elements can becharacterized by a polynomial, or different polynomials. The differentpolynomials can have different terms, different coefficients, or both.The first optical element is positioned at a particular distance fromthe second optical element such that the second surface of the firstoptical element faces the second surface of the second optical element,where each of the first and the second optical elements is configured tomove substantially perpendicular to the optical axis.

Another aspect of the disclosed embodiments relates to an Alvarez lensconfiguration that includes a first optical element and a second opticalelement, where each optical element includes two surfaces that aresubstantially perpendicular to an optical axis of the lensconfiguration. A first surface of each the optical elements is afreeform surface and a second surface of each of the optical elements isa surface characterized by a polynomial. The first optical element ispositioned at a particular distance from the second optical element suchthat the second surface of the first optical element faces the secondsurface of the second optical element, where each of the first and thesecond optical elements is configured to move substantiallyperpendicular to the optical axis.

In one exemplary embodiment, the first optical element is configured tomove synchronously with the second optical element and in oppositedirection of the movement of the second optical element. In anotherexemplary embodiment, the first and the second optical elements areconfigured to move perpendicular to the optical axis by the same amountbut in opposite directions.

In some embodiments with any of the above described systems, a z-heightof no more than 6 mm is achieved, and a z-height in the range of 4-7 mmcan be achieved over a range of optical powers, for example in the rangeof 1× to 6×. In some embodiments with any of the above describedsystems, a field of view in the range 60 degrees to 75 degrees isachieved.

Another aspect of the disclosed embodiments relates to a method formanufacturing a miniature lens system that includes producing astructural platform comprising a frame and an arm, and molding aplurality of optical elements onto the frame of the structural platformsubsequent to, and as a separate step from, producing the structuralplatform, the plurality of optical components comprising: a firstvarifocal lens, a first prism and a first base lens. In one exemplaryembodiment, producing the structural platform comprises molding the armonto the frame of the structural platform. In another exemplaryembodiment, the above noted method further includes connecting one ormore actuators to the arm of the structural platform, the one or moreactuators being coupled to one or more of the optical elements to allowmovement of the one or more optical elements. In still another exemplaryembodiment, the above noted method further comprises bonding awafer-level optical component with a preformed lens element to thestructural platform.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the dimensional tolerance versus component dimension fora precision injection molding regime that is implemented in accordancewith the disclosed embodiments and other techniques.

FIG. 2 illustrates a sequence of operations that can be carried out tofabricate an integrated optical system in accordance with an exemplaryembodiment.

FIG. 3 illustrates a top view of a fabricated molded structure inaccordance with an exemplary embodiment.

FIG. 4 illustrates a set of operations that can be carried out toproduce an integrated optical device in accordance with an exemplaryembodiment.

FIG. 5 illustrates a set of operations that can be carried out toproduce an integrated optical device in accordance with an exemplaryembodiment.

FIG. 6 illustrates a set of operations that can be carried out inaccordance with another exemplary embodiment to produce an integratedoptical device.

FIG. 7 depicts an optical system in which the optical path is foldedtwice and varifocal lenses are located in between the folding optics inaccordance with an exemplary embodiment.

FIG. 8 depicts an optical system with varifocal lenses located at thewindow, the optical path being folded before reaching the secondvarifocal lens and folded again before reaching the complementarymetal-oxide semiconductor (CMOS) detector in accordance with anexemplary embodiment.

FIG. 9 depicts an optical system comprising a varifocal lens elementintegrated with a prism element and a CMOS detector placed verticallyupright in accordance with an exemplary embodiment.

FIG. 10 is a ray diagram for an optical system in accordance with anexemplary embodiment.

FIG. 11 is a ray diagram for an optical system in accordance withanother exemplary embodiment.

FIG. 12 illustrates a pair of varifocal lenses that include planarsurfaces in accordance with an exemplary embodiment.

FIG. 13 illustrates a pair of varifocal lenses that include freeformsurfaces in accordance with an exemplary embodiment.

FIG. 14 depicts the active area of an Alvarez-like lens in accordancewith an exemplary embodiment.

FIG. 15 depicts an exemplary prism element with a freeform surface thatcan be utilized within at least one optical system of the disclosedembodiments.

FIG. 16 depicts an integrated lens platform and its associatedcomponents in accordance with an exemplary embodiment.

FIG. 17 illustrates a set of operations that can be carried out inaccordance with an exemplary embodiment to produce a miniature lenssystem.

FIG. 18 illustrates an embodiment of a miniaturized optical zoom lenssystem comprising, in sequence along a light path, a first varifocallens, a prism and optional iris, a second varifocal lens, and a baselens group, all configured to create an image on a image sensor ordetector.

FIG. 19 illustrates an embodiment of a miniature optical zoom lenssystem comprising, in sequence along a light path, a first varifocallens, a prism and optional iris, a single fixed freeform lens, a secondvarifocal lens, and a base lens group, all configured to create an imageon a image sensor.

FIG. 20 illustrates an embodiment of a miniature optical zoom lenssystem comprising, in sequence along a light path, a first varifocallens, a prism and optional iris, a second varifocal lens groupcomprising three freeform lenses in which two move together, and a baselens group, all configured to create an image on an image sensor.

FIG. 21 illustrates an embodiment of a miniature optical zoom lenssystem comprising, in sequence along a light path, a first varifocallens, a prism and optional iris, a second varifocal lens, a base lensgroup, and a freeform lens, all configured to create an image on animage sensor.

FIG. 22 illustrates an embodiment of a miniature optical zoom lenssystem comprising, in sequence along a light path, a first varifocallens, a prism and optional iris, a fixed rotationally symmetric lens, asecond varifocal lens, and a base lens, all configured to create animage on an image sensor.

FIG. 23 illustrates an embodiment of a miniature optical zoom lenssystem comprising, in sequence along a light path, a first varifocallens, a prism and optional iris, a second varifocal lens, a first baselens group which is movable, and a fixed base lens group, all configuredto create an image on an image sensor.

FIG. 24 illustrates in detail a configuration of the elements of avarifocal lens wherein each of the optically important surfaces aredefined by polynomials, although the polynomial defining each surfacecan vary from the polynomial defining the other surfaces, includingvarying the number of terms and the coefficients.

The disclosed embodiments relate to methods, devices, and fabricationprocesses that facilitate design and manufacturing of optical systemswith improved alignment capabilities and reduced overall size, inaddition to disclosing systems and methods for configuring componentswithin an optical system.

To achieve movement of an optical component, such as a lens, along theoptical axis (i.e., z-axis) or perpendicular to the optical axis (i.e.,along the x- and y-axes), in an embodiment spring flexures can beutilized to allow the optical component to move laterally. The springflexures can be simple beams or cascaded beam flexures. Alternatively,voice coil motors can be used to achieve the necessary movement.

In one approach, the lens element in an optical system can be fabricatedthrough a molding process whereby a mold is created and liquid plasticresin is injected into the mold and hardened through UV or heat. Thespring flexures can be fabricated separately, for example using microfabrication processes. The lens element and the spring flexures can thenbe assembled. In this approach, however, alignment can be one majorconcern. For example, unlike typical spherical lens elements, free-formsurfaces may not have rotational symmetry. Thus, besides the usualin-plane positioning issues, there is an additional rotational alignmentbetween the lens element and the spring flexure structure. The actualstep of assembly, whether through adhesives or other means, may alsopotentially disturb the alignment process.

The disclosed embodiments facilitate alignment of optical components inan optical system that can include optical components with spheric,aspheric, and/or free-form surfaces that may further move in anydirection within the optical system. In some embodiments, monolithicintegration of the lens element, spring flexures, and supportingstructures minimizes the number of post-assembly steps for integrationand reduces possible misalignment issues.

Some of the disclosed embodiments rely on injection precision molding tofabricate optical systems that can include lenses and other opticalcomponents, as well as mechanical components such as flexible or rigidfixtures. FIG. 1 provides a comparison of dimensional tolerance versuscomponent dimensions for a precision injection molding regime that isimplemented in accordance with the disclosed embodiments. As illustratedin FIG. 1, precision injection molding enables the manufacture ofsmaller components with better tolerances compared to other techniques.As will be described in the sections that follow, multiple shots ofinjection molding can be sequentially introduced to produce integratedmicro-optic devices in accordance with the techniques of the disclosedembodiments.

According to the disclosed embodiments, the lens and the flexures of anintegrated optical device can be fabricated in a single step. This canbe achieved in several ways. The lens element is essentially arefractive element with a certain surface profile. The required surfaceprofile can be fabricated through casting from a mold. Fabrication ofthe lens together with the spring flexures can be accomplished byturning the additional spring flexures on the same mold as the lens. Assuch, when the plastic resin is injected into the mold, the resultingstructure is a lens element with the spring flexures attached thereto.In this way, lens elements casted out separately can be assembled withthe supporting structure. Other parts of the structure can be molded inthe same step, as well. By way of example, and not by limitation, suchother parts can include structures for assembly with other lens elementsor structures for positioning and alignment.

In scenarios where a single-shot molding process is not feasible due to,for example, limitations in design flexibility, a multi-shot (e.g.,two-shot, three-shot, four-shot, etc.) precision injection moldingfabrication process can be used to fabricate the integrated opticalsystem. For example, in a two-shot fabrication process, the first shotcan cast out the spring flexures, and the second mold for the secondshot can cast out the lens element integrated with the previously castspring flexures. As the mold is removed, further fine-tuning on thedimensions can be done, if needed, through on-the-spot micromachining,such as with a precision computer numerical control (CNC) machine.

According to some embodiments, metal stamping can additionally, oralternatively, used to mass-produce parts in a cost-efficient manner. Inthis case, the metal stamping mold can create the spring flexureskeleton structure that can be used to reinforce the subsequent moldingstep. The molding step can then cast out the lens element on the metalskeleton structure.

Besides molding the lens element on the metal skeleton structure, thelens elements can be molded in a separate process. This may be carriedout to minimize the stress on the active lens area during the moldingprocess. In such scenarios, the lens elements can be assembled onto theskeleton structure through a separate process such as ultrasonic weldingor adhesives

According to some embodiments, micro-fabrication methods canadditionally, or alternatively, be used to produce a chip-based mold.The chip or wafer produced using micro-fabrication techniques caninclude etched-out grooves that correspond to the locations of thespring flexures. The lens element can then be cast out separately andpositioned on individual chips or wafers. Ultraviolet (UV) orheat-curable resin can then be poured to fill out the grooves togetherwith the lens elements and subsequently cured. The resulting plasticpiece is now a lens element with the spring flexures attached andaligned.

In another iteration, the above described fabricated integratedspring-flexure-lens can then be further assembled either with othercomponents or another spring-flexure-lens assembly using one or more ofthe above-described techniques. As such, other structures can beincorporated into the molding process. Since other components also needto be assembled, some alignment structures can be molded as part of theoverall structure.

In embodiments that require the movement of one or more opticalcomponents, an actuation mechanism is needed to move the lens. Thisactuation mechanism can also be incorporated into the mold design. Forexample, electromagnetic actuation can be implemented using a miniaturecoil of wire that is assembled on the integrated spring-flexure-lens. Tothis end, a groove can be designed to hold the miniature coil of wire onthe integrated spring-flexure-lens.

As noted earlier, further refinements can be undertaken immediatelyafter the plastic resin step through, for example, a precisionmicromachining that is performed on the cast plastic structure tofurther improve the tolerance of the components.

FIG. 2 illustrates a sequence of operations that can be carried out tofabricate an integrated optical system in accordance to an exemplaryembodiment of the invention. The operations in FIG. 2 start with thecreation of the elastic suspension mold. Next, the first shot of elasticsuspension material is injected into the mold. Then, a second shot castsout the lens. Upon removal of the lens mold (in (d)) and removal of theintegrated device (in (e)), the elastic suspension frame and the microlens is obtained. Although the exemplary operations in FIG. 2 depict thefabrication process for a single-lens assembly with elastic suspensionstructures, it is understood that additional optical, mechanical(including alignment) structures can be integrated into the opticalsystem through the existing or additional injection molding steps.Moreover, these additional structures can be rigid or elastic.

FIG. 3 illustrates a top view of a molded structure fabricated inaccordance with an exemplary embodiment of the invention. The structurethat is illustrated in FIG. 3 includes a supporting structure, a lenselement, a holder for the lens actuator and elastic (e.g., spring)fixtures that allow the lens to be moved in the up/down directionindicated by the arrow. While the exemplary structure of FIG. 3 onlyshows movement of the lens in a single direction, it is understood thatmovement of the lens in three dimensions can be enabled. For example,additional elastic fixtures and appropriate actuation mechanisms can beincluded in the structure.

Further, alternate or additional optical components can be incorporatedinto the integrated systems that are fabricated in accordance with thedisclosed embodiments. These components can include, but are not limitedto, lenses, gratings, diffractive optical elements and the like. Thedisclosed embodiments provide for a sequence of manufacturing processeswith tolerances in the region of 1 to 5 microns for an integratedplatform incorporating elastic suspension, rigid frames, and opticalcomponents. The cost of manufacturing these components is estimated tobe much lower than conventional MEMS micro fabrication.

Precision manufacturing technologies that are used for fabrication ofthe integrated systems in accordance with the disclosed embodiments caninclude injection molding, in-mold decoration, hot stamping, and/orinsert molding. These processes allow mass manufacturing of integratedoptical systems that can include a microlens on an elastic suspensionplatform. In some embodiments, the elastic suspension is made with ametal backbone that is fabricated using, for example, metal stampingfollowed by a polymer molding (first shot). The metallic frames canenhance the elasticity of the suspension and robustness of the frame. Insome embodiments, the elastic suspension is made without the metalbackbone. The second shot can be a polymer material suitable for anoptical lens. This component is then assembled into a larger structuremaking up an optical lens module. Multiple shots of injection moldingprocess steps can be incorporated for multi-component integration.

FIG. 4 illustrates a set of operations 400 that can be carried out inaccordance with an exemplary embodiment to produce an integrated opticaldevice. At 402 a first mold is obtained that is structured to form anelastic suspension fixture. At 404, a first injection material isinjected into the first mold. At 406 a second mold is placed in contactwith the first mold and with the first injection material within thefirst mold. The second mold is structured to form an optical element. At408, a second injection material is injected into the second mold. At410 the second mold is removed and at 412 the first mold is removed toobtain the elastic suspension fixture with the optical elementintegrated thereto.

FIGS. 5 and 6 illustrate two sets of operations 500 and 600,respectively, that can be carried out in accordance with other exemplaryembodiments to produce an integrated optical device. In the exemplaryembodiment of FIG. 5, at 502, a first mold is obtained that isstructured to form an elastic suspension fixture and an optical element.At 504, a first injection material is injected into the first mold and,at 506, a second injection material is injected into the first mold. At508, the first mold is removed to obtain the elastic suspension fixturewith the optical element integrated thereto. In the exemplary operations600 of FIG. 6, at 602, a mold is obtained that is structured to form anelastic suspension fixture and to house an optical element. At 604, theoptical element is placed in the mold and, at 606, a first injectionmaterial is injected into the mold to form an elastic suspensionfixture. At 608, the mold is removed to obtain the elastic suspensionfixture with the optical element integrated thereto.

Zoom Lens Configuration

In applications with limited space (e.g., in a camera phone) theconfiguration of optical components significantly influences the size ofthe overall camera module that can be achieved. In such systems, thethickness (e.g., the thickness of the device in z-direction or“z-height”) of the module is paramount. In order to deliver the smallestpossible optical configuration for a zoom lens system, severalconfigurations are disclosed in this application.

As shown in FIG. 7, one embodiment features a light path-bendingelement, such as a prism 702 or a mirror, which is used to bend incomingrays 90 degrees, sending them through two varifocal lenses 704, 706 andanother prism 708, which bends the optical path again for it to reachthe detector (e.g., CMOS detector 710). In an exemplary embodiment, thefixed/base lens 714 is integrated with the prism 708, and the aperture712 is placed in-between the two varifocal lenses 704, 706. Such aconfiguration offers the shortest z-height possible but suffers fromlimited field of view (FOV) and f-numbers. In this configuration, whileit is possible to achieve a thin z-height of 6 mm, the FOV is limited toabout 30°.

In order to increase the FOV, in some embodiments, at least one of thevarifocal lenses may be located at the entrance of the optical system,as shown in FIG. 8. In the exemplary configuration of FIG. 8, a prism802 is placed in-between the two varifocal lenses 804, 806 to bend theoptical path 90 degrees and another prism 808 is used to bend the lightan additional 90 degrees before reaching the detector (e.g., the CMOSdetector 810). The aperture 812 is located between the prism 802 and thevarifocal lens 806. The exemplary configuration of FIG. 8 allows a FOVof 60° to 75°. The z-height has to be increased to about 8 mm. FIG. 8illustrates an exemplary configuration in which the detector is placedon the same side as the entrance of the optical system. However, it isunderstood that the detector can be placed on the side opposite to theentrance of the optical system (as, for example, illustrated in theconfiguration of FIG. 7). Placing the detector at the same side canminimize the z-height of the module since the increase in z-height isprimarily due to the additional height of the lens and detectorelements. Thus placing the detector 810 on the same side as the entrancewindow means that the z-height is increased only by the thicker of thetwo elements. However, since the optical path to reach the detector isrelatively long, considering the need for the path to be folded beforereaching the detector, the aperture and beam diameter is stillrelatively large in this configuration. An approach to shorten theoptical path length to reach the detector can reduce the z-height evenfurther.

To reduce the optical path length to reach the detector, in accordancewith some embodiments, the detector is placed vertically upright andtherefore closer to the lenses, as shown in FIG. 9. In the exemplaryconfiguration of FIG. 9, a prism-like element 904 that includes a firstvarifocal lens integrated with a prism component is placed between thewindow receiving the incident light and the second varifocal lens 906.Thus, the need for a second prism element is removed. The aperture 912is located between the integrated varifocal lens and prism 904 and thesecond varifocal lens 906. The overall optical path length can bereduced from about 23 mm to about 18 mm. The reduction in optical pathlength allows a smaller aperture diameter along with smaller lenselements and therefore also smaller z-height. A z-height ofapproximately 6 mm can be obtained in this configuration. As anotherexample, a z-height of between about 4-7 mm can be achieved, with theparticular z-height affected by the optical power of a particulardesign. Without the varifocal lens integrated with the prism, thez-height will have to be increased slightly, to about 6.5 mm, toaccommodate the gap between the varifocal lens and prism. In thisconfiguration, a FOV in the range of 60°-75° can be achieved. Dependingon the application, optical specification of the disclosed zoom lensescan be modified to meet the required size and form factor. For example,the z-height can be further reduced to meet specific implementationrequirements.

FIG. 10 illustrates a ray diagram for a miniature lens configuration inaccordance with an exemplary embodiment. The configuration of FIG. 10provides a specific example of the lens system of FIG. 9 in which bothvarifocal lenses 1004 and 1006 are alvarez-like lenses. In addition, thevarious optical components in FIG. 10 are positioned to obtain thedesired zoom capability. In particular, the first pair of Alvarez lenses1004 is positioned to receive incident light from the entrance to theminiature lens system, and direct the light to the integrated prism.Although the exemplary diagram of FIG. 10 shows an integrated Alvarezlens-prism, it is understood that in some embodiments, the first Alvarezlens and the prism may be separate components. Referring back to FIG.10, the light that enters the integrated prism is bent by 90 degreesbefore exiting the prism. The light is then received by the secondAlvarez lens 1006, and subsequently travels through the Fixed/base lensgroup 1014 before reaching the detector 1010. In the example diagram ofFIG. 10, by moving the two elements of the first Alvarez lenses 1004perpendicular to the optical axis at opposite directions (e.g., one lenselement is moved out and the other lens element is moved into the page),a negative optical power is produced. Further, in the exemplary diagramof FIG. 10, by moving the two elements of the second Alvarez lens 1006perpendicular to the optical axis at opposite directions, a positiveoptical power is effectuated. The movement of the lens elements can beachieved using one or more actuators that are coupled to the lenselements. The exemplary configuration of FIG. 10 produces a miniaturelens system with a small height, which makes this configurationparticularly advantageous for implementation in devices with thin formfactors, such as a cell phone or tablet.

FIG. 11 illustrates a ray diagram for a miniature lens configuration inaccordance with another exemplary embodiment. The configuration of FIG.11 provides yet another specific example of the lens system of FIG. 9 inwhich both varifocal lenses 1104 and 1106 are alvarez-like lenses. Inaddition, the various optical components in FIG. 11 are positioned toobtain the desired zoom capability. In particular, the first pair ofAlvarez lenses 1104 is positioned to receive incident light from theentrance to the miniature lens system, and direct the light to theintegrated prism. The light that enters the integrated prism is bent by90 degrees before exiting the prism. The light is then received by thesecond Alvarez lens 1106, and subsequently travels through theFixed/base lens group 1114 before reaching the detector 1110. In theexample diagram of FIG. 11, by moving the two elements of the firstAlvarez lenses 1104 perpendicular to the optical axis at oppositedirections (e.g., one lens element is moved out and the other lenselement is moved into the page), a positive optical power is produced.Further, in the exemplary diagram of FIG. 11, by moving the two elementsof the second Alvarez lens 1106 perpendicular to the optical axis atopposite directions, a negative optical power is effectuated. Themovement of the lens elements can be achieved using one or moreactuators that are coupled to the lens elements. As is illustrated inFIG. 11 by the circled X and circled dot markings on the Alvarez lenselements, the movements of the lens elements are opposite to thoseillustrated in FIG. 10. By changing the optical power of the two pairsof Alvarez lenses, the focal length of optical system changes. In theexemplary diagram of FIG. 10, the lens system operates as a telescopewith a long focal length.

FIG. 12 illustrates a lens configuration that includes two varifocallenses in accordance with an exemplary embodiment. Each of the firstvarifocal lens 1202 and the second varifocal lens 1204 comprises twolens elements comprises two elements (FIG. 12 illustrates elements 1 and2 for the first lens 1202, and elements 3 and 4 for the second lens1204). Each element is considered a thin plate, where each plate ischaracterized by two surfaces that are generally perpendicular to theoptical axis. One surface is a plane surface and the other surface is apolynomial surface which is characterized by a function (e.g., apolynomial). The non-planar surface is designated as Alvarez surface inFIG. 12. For each of the lenses 1202 and 1204, by placing the two platesat a small distance from one another, and with the polynomial surfacesfacing one another, an optical power is generated. By moving the twoelements perpendicular to the optical axis at opposite directionssynchronously, the optical power can be varied.

FIG. 13 illustrates a lens configuration that includes two varifocallenses in accordance with another exemplary embodiment. The exemplaryconfiguration of FIG. 13 includes a first varficoal lens 1302 and asecond varifocal lens 1304 similar to those depicted in FIG. 12.However, instead of plane surfaces, the elements 1, 2, 3 and 4 in FIG.13 each include a freeform surface that is shaped to correct aberrationsin the optical system.

In each of the disclosed embodiments, the varifocal lenses can be, amongother types, liquid crystals, liquid lenses, or Alvarez-like lenses. Thevarifocal lenses can also be made up of multiple lens elements, as inthe case of Alvarez-like lenses. For each of the embodiments, it wouldnot be feasible to configure conventional lenses for a small z-heightmodule since a conventional lens moving along the optical axis wouldincrease the z-height significantly. Further, to achieve a large FOV, atleast one varifocal lens must be located at the entrance of the opticalmodule.

Lens Active Area

The disclosed embodiments include additional improvements that furtherreduce the z-height of the optical module. In some embodiments that useAlvarez-like lenses, the Alvarez-like lenses are moved perpendicular tothe optical path (instead of along the optical path) to perform tuning.Moreover, displacement of the Alvarez-like lenses perpendicular to theoptical axis has a significant impact on the performance of the opticalmodule. In particular, a larger displacement of the lens can result in agreater change of optical power. However, given that only a portion ofthe lens area is being utilized at a given position of the lenses (i.e.,an “actual active area” of the lens), a larger displacement of thelenses also results in requiring a larger circular lens diameter tocover the active area. This scenario can be further illustrated with theaid of FIG. 14, in which the small circles represent two actual activeareas of a varifocal lens at two different lens positions (i.e.,displaced from one another perpendicular to the optical axis). While thediagram in FIG. 14 shows active areas of the same size for illustrationpurposes, the sizes of the actual active areas may not be the same. Inthe exemplary diagram of FIG. 14, the optical axis pointing in and outof the page. The large circle in FIG. 14 represents the circular areaneeded to encompass the active area of any single lens as the lens movesin x- and/or y-directions. The rectangular area represents the smallersingle lens profile that is sufficient for the operation of the lens.The length of the rectangular area would typically represent thedirection of motion.

In some embodiments, instead of a circular lens, a rectangular oroval-shaped lens that only covers the essential active area of thelenses is used. Such a lens in rectangular format is shown by therectangular block in FIG. 14. In this manner, the actuation range can beincreased without affecting the overall optical module size. Rotationalalignment can be improved during assembly and fabrication.

Freeform Prism

According to some embodiments, the size of the optical system can befurther reduced by combining the prism and varifocal lens elements. Thisis particularly relevant when Alvarez-like lenses are used. Using thistechnique, one of the sides of the prism can be molded with a freeformsurface, as shown in FIG. 15, allowing additional gap space between thevarifocal lens surfaces to be removed.

Integrated Platform

In moving lenses perpendicular to the optical axis, the mechanism has tobe small, compact, and easily aligned and manufactured. Having the lenselement integrated with a structural platform is a way of fulfillingthese requirements. FIG. 16 shows an integrated platform in accordancewith an exemplary embodiment. As shown in FIG. 16, the integratedplatform comprises a frame that serves as a structural guide and an armelement that connects to an actuator element, such as a coil or magnet.The lens element can be directly molded or fabricated onto the framewith the correct orientation. A spring flexure element may or may not beincorporated with the integrated platform. In one embodiment, theplatform frame and arm are molded in one step and the lens elementmolded after that. In another embodiment, the frame can be made of alead frame metal structure. The lead frame can be metal-stamped,laser-cut, milled, etched, or molded. The arm element can be molded onthe lead frame structure by an injection molding process, with the lenselement molded onto the lead frame after the rest of the structures arecompleted.

In order for the molded lens to be aligned accurately, alignmentstructures can be incorporated onto the platform. Besides insert moldingthe lenses, a wafer-level optical component with a preformed lenselement can be bonded to the platform in a separate step. All of theseprocesses are intended to allow the manufacturing process to beautomated, keeping the overall structure compact and ensuring accuratealignment between structures and lens elements.

In actuating the integrated lens platform, incorporating a springflexure element may or may not be necessary. A spring flexure primarilyserves to provide a restoring force to the platform. This is necessaryif the actuation mechanism is only capable of providing a force in asingle direction, as in the case with a voice-coil actuator with asingle-direction drive. A voice-coil actuator with a bidirectional drivecan remove the need for a flexure-restoring element. Without the springflexure element, the actuation range can be easily increased. By addinga position sensor on the system, the position of the lens platform canbe well determined through a closed-loop control.

In some embodiments, the actuation requirement is simplified when two ormore lenses are designed to move with the same displacement anddirection. In this way, instead of having individual actuators for eachlens element, one actuator is used to move two or more lenses. Amechanical structure can be designed to link the multiple lensestogether. The structure is then actuated by an actuator.

Zoom and Focus Decouple Operation

Focusing and zoom are two operations that the optical system has to beable to perform. Regardless of the configuration that is used, the firstvarifocal lens element can be used for focusing purposes when the secondvarifocal lens is kept constant at a particular optical power. Operationin such a manner can be very elegant given the cost of more complexelectronics and more constraints in terms of the optical optimizationthat has to be performed on the optical system.

To simplify the operation of the system, in some embodiments, the zoomand focusing operations are decoupled. Zoom is delivered through thetuning of the two varifocal lenses. Focusing can be performed throughmoving the base lens system along the optical axis. This simplifies theimage optimization process and controls. In such embodiments, anactuator group actuates the varifocal lenses as a group. Focusing can beachieved through either moving the base lens group along the opticalaxis or a tunable lens element or elements in the base lens group.Suitable elements are optical lenses that can change their opticalpower, such as liquid lenses, liquid crystals, MEMS-based lenses,Alvarez-like lenses, and piezo-based lenses.

FIG. 17 illustrates a set of operations 1700 that can be carried out inaccordance with an exemplary embodiment to produce a miniature lenssystem. At 1702, a structural platform comprising a frame and an arm isproduced. At 1704, a plurality of optical elements are molded onto theframe of the structural platform subsequent to, and as a separate stepfrom, producing the structural platform. The plurality of opticalcomponents comprising: a first varifocal lens, a first prism and a firstbase lens. In one exemplary embodiment, producing the structuralplatform comprises molding the arm onto the frame of the structuralplatform. In another exemplary embodiment, the above noted methodfurther includes connecting one or more actuators to the arm of thestructural platform. The one or more actuators are coupled to one ormore of the optical elements to allow movement of the one or moreoptical elements. In yet another exemplary embodiment, the above methodfurther includes bonding a wafer-level optical component with apreformed lens element to the structural platform.

FIGS. 18-23 illustrate various alternative embodiments of miniatureoptical lens systems, all configured to create an image on an imagesensor which is typically supplied separately from the presentinvention. In particular, FIG. 18 illustrates an embodiment of aminiaturized optical zoom lens system comprising, in sequence along anoptical path, a first varifocal lens 1800 comprised of a pair ofAlvarez-like optical elements 1805 and 1810, a prism 1815 and optionaliris 1820, a second varifocal lens 1825 again comprised of a pair ofAlvarez-like optical elements 1830 and 1835, and a base lens group 1840comprising a plurality of rotationally symmetric lenses, illustrated as1840A-C, all configured to create an image on a image sensor ordetector. The optical elements 1805, 1810, 1830 and 1835 of the firstand second varifocal lenses 1800 and 1825, respectively, are configuredto move perpendicularly to the light path to provide at least variableoptical power, and one or both of the optically important surfaces ofeach optical element can be, depending on the implementationrequirements, defined by a polynomial as described in greater detailhereinafter in connection with FIG. 24. The movement of the opticalelements may either be individual or as pairs, such as, for example, apairing of 1805-1830 and 1810-1835, or 1805-1835 and 1810-1830, all astaught in greater detail in commonly assigned PCT patent applicationPCT/IB2015/000409, incorporated herein by reference. The base lens groupmoves along the optical path and optically combines with the varifocallenses to provide a focused image on a separately-supplied sensor. Anactuator, which may comprise a plurality of actuators, [not shown forclarity of illustration] provides relative movement of the varifocallenses as well as the base lens group. In some embodiments a secondprism may be positioned between the base lens group and the sensor toagain bend the light 90 degrees and enable reduced z-height of thecamera, since, in the absence of the second prism, the size of thesensor may require a greater z-height of the completed camera once thesensor is mated to the lens system of the present invention. It willalso be appreciated that, in some embodiments, the sensor itself can bemoved along the optical path for purposes of, for example, achievingimproved or simplified focusing, or the entire lens system can be movedrelative to the sensor for these same purposes. In an embodimentsuitable for use in a mobile device, the travel of the sensor can be inthe range of 0.2 mm to 1 mm. A separate actuator can be implemented tocontrol such movement. It will be appreciated by those skilled in theart that the above description of individual or pair-wise movements,actuators, second prism, and so on, apply to each of the alternativesdescribed herein and, for the sake of clarity, will not be repeated.

Referring next to FIG. 19, the alternative embodiment illustratedtherein comprises in sequence along the optical path, a first varifocallens 1900 comprised of a pair of Alvarez-like optical elements 1905 and1910, a prism 1915 and optional iris 1920, a single fixed Alvarez-likefreeform lens or optical element 1925, a second varifocal lens 1930comprising a pair of Alvarez-like optical elements 1935 and 1940, and abase lens group 1950 comprising, for example, rotationally symmetricallenses 1950A-C, all configured to create an image on an image sensor1955. The freeform lens 1925 is fixed in position and can have one orboth surfaces defined by the same or different polynomials, and also thesame as or different from the polynomial(s) that define the surfaces ofthe varifocal lenses 1900 and 1925, as discussed in greater detailhereinafter in connection with FIG. 24. As discussed above, opticalelements 1905, 1910, 1925 and 1930 move perpendicularly to the opticalaxis. The combination of the fixed optical element 1925 with thevarifocal lenses can aid in focusing and aberration and distortioncorrection as well as reducing the optical power that must otherwise beprovided by varifocal lenses 1900 and 1930.

Next, with reference to FIG. 20, an embodiment of a miniature opticalzoom lens system is illustrated which comprises, in sequence along theoptical path, a first varifocal lens 2000 comprising Alvarez-likeoptical elements 2005 and 2010, a prism 2015 and optional iris 2020, asecond varifocal lens group 2025 comprising three freeform opticalelements 2030, 2035 and 2040, in which optical elements 2030 and 2040move together along the same path while optical element 2035 moves inthe opposite direction, and a base lens group 2045 comprisingrotationally symmetrical lenses 2045A-C, all configured to create animage on an image sensor 2050. As with the embodiment of FIG. 19, theaddition of optical element 2030 can aid in focusing, aberration anddistortion correction, as well as reducing the optical power requiredfrom the remaining Alvarez-like elements.

FIG. 21 illustrates an embodiment of a miniature optical zoom lenssystem comprising, in sequence along the optical path, a first varifocallens 2100 comprising Alvarez-like optical elements 2105 and 2110, aprism 2115 and optional iris 2120, a second varifocal lens 2125comprising optical elements 2130 and 2135, a base lens group 2140comprising, for example, symmetrical lenses 2140A-C, and a freeform lens2145 which can be either fixed or movable, depending upon the designrequirements of the implementation, all configured to create an image onan image sensor 2150. The varifocal lenses are configured and operate asdescribed above, and the freeform lens element 2145 can have one or bothsurfaces defined by the same or different polynomials, again asdescribed in connection with FIG. 24. Depending upon the particulardesign requirements, the lens element 2145 can aid in focusing,aberration and distortion correction, as well as providing optical powerin some instances.

Referring next to FIG. 22, the embodiment of a miniature optical zoomlens system illustrated therein comprises, in sequence along the opticalpath, a first varifocal lens 2200 comprising Alvarez-like opticalelements 2205 and 2210, a prism 2215 and optional iris 2220, arotationally symmetric lens 2225, a second varifocal lens 2230comprising Alvarez-like optical elements 2235 and 2240, and a base lens2245 and comprising, for example, three rotationally symmetrical lenses2245A-C, all configured to create an image on an image sensor 2250. Thelens 2225 is shown as fixed, but in some embodiments can be movablealong the optical axis. As before, the lens 2225 can aid in focusing andaberration and distortion correction, and may in some embodiments aid inproviding optical power.

FIG. 23 illustrates an embodiment of a miniature optical zoom lenssystem comprising, in sequence along a light path, a first varifocallens 2300 comprising Alvarez-like optical elements 2305 and 2310, aprism 2315 and optional iris 2320, a second varifocal lens 2325comprising optical elements 2330 and 23355, a first base lens group2340, illustrated as having, for example, two rotationally symmetricallenses 2340A-B, and a second base lens group 2345, shown as fixed andcomprising a single rotationally symmetrical lens but which, dependingupon the design requirements, can be movable along the optical axis andmay comprise more than one lens. As before, the overall function of thelens system of the present invention is to create a clear image on animage sensor which benefits for variable optical power. The separationof the base lens into two groups can facilitate focusing as well asaberration and distortion correction.

FIG. 24 illustrates in detail a configuration of the elements of avarifocal lens 2400 and having Alvarez-line optical elements 2405 and2410 wherein each of the optically important surfaces are defined bypolynomials, although the polynomial defining each surface can vary fromthe polynomial defining the other surfaces, including varying the numberof terms and the coefficients.

It is understood that the operations that are described in the presentapplication are presented in a particular sequential order in order tofacilitate understanding of the underlying concepts. It is alsounderstood, however, that such operations may be conducted in adifferent sequential order, and further, that additional or fewer stepsmay be used to carry out the various disclosed operations.

The foregoing description of embodiments has been presented for purposesof illustration and description. The foregoing description is notintended to be exhaustive or to limit embodiments of the presentinvention to the precise form disclosed, and modifications andvariations are possible in light of the above teachings or may beacquired from practice of various embodiments. The embodiments discussedherein were chosen and described in order to explain the principles andthe nature of various embodiments and their practical application toenable one skilled in the art to utilize the present invention invarious embodiments and with various modifications as are suited to theparticular use contemplated. The features of the embodiments describedherein may be combined in all possible combinations of methods,apparatus, modules, systems, and articles of manufacture.

What is claimed is:
 1. A miniature zoom lens system, comprising: a firstprism positioned on an optical axis to receive incident light from anentrance to the miniature lens system through a first face of the firstprism and to bend the received light by approximately 90 degrees beforeallowing the light to exit from a second face of the first prism; a pairof varifocal lenses, each comprising at least two optical elements andeach optical element having at least one optical surface defined by apolynomial, and wherein at least one of the pair of varifocal lenses ispositioned to receive light that exits from the second face of theprism; each of the optical elements being formed integrally with aframe, at least one base lens positioned substantially along the opticalaxis to receive light after passing through the pair of varifocallenses; and a first actuator configured to connect to the frames of theoptical elements to move the pair of varifocal lenses in a directionsubstantially perpendicular to optical axis.
 2. The system of claim 1,wherein the lens and frame are formed integrally by injection molding.3. The system of claim 1, wherein the first varifocal lens is one of thefollowing: a liquid crystal lens, a liquid lens, or an Alvarez-likelens.
 4. The system of claim 1 wherein at least two surfaces of at leastone of the optical elements are defined by polynomials.
 5. The system ofclaim 1, wherein the first actuator comprises one of a coil or a magnet.6. The system of claim 1, further comprising a structural platform toallow one of the following to be directly molded onto, fabricated onto,or integrated with the structural platform: the first prism, a secondprism, the first varifocal lens, or a second varifocal lens.
 7. Thesystem claim 6, wherein the structural platform comprises a springflexure element.
 8. The system claim 6, wherein the structural platformincludes a frame and an arm.
 9. The system claim 8, wherein: thestructural platform frame comprises a lead frame metal structure that isone or more of: a metal-stamped structure, a laser-cut structure, amilled structure, an etched structure, or a molded structure; the arm ismolded on the lead frame structure; and one or more of the first prism,a second prism, the first varifocal lens, or a second varifocal lens ismolded onto the lead frame.
 10. The system of claim 6, wherein awafer-level optical component with a preformed lens element is bonded tothe platform.
 11. The system claim 1, wherein the first actuator is avoice-coil actuator with a bidirectional drive.
 12. The system claim 1,comprising second actuator configured to move an optical component otherthan the first varifocal lens within the miniature zoom lens system. 13.The system of claim 12, wherein the second actuator and the firstactuator are configured to displace both the optical component otherthan the first varifocal lens and the first varifocal lens by the samedistance and in the same direction.
 14. The method of claim 13, whereinthe optical component other than the first varifocal lens is one of: asecond varifocal lens, the at least one base lens, the first prism, or asecond prism.
 15. The system claim 1, wherein the first varifocal lenshas a rectangular or an oval-shaped cross section encompassing only anessential active area of the first varifocal lens.
 16. The system claim1, further comprising a second varifocal lens positioned to receive thelight exiting the first varifocal lens before reaching the at least onebase lens.
 17. The system of claim 16, wherein the second varifocal lenshas a rectangular or an oval-shaped cross section encompassing only anessential active area of the second varifocal lens.
 18. The system ofclaim 16, wherein the optical elements of both the first and the secondvarifocal lenses are movable with respect to one another so as toprovide optical zoom capability for the lens system.
 19. The systemclaim 1, wherein the at least one base lens is configured to move alongthe optical axis of the system to provide optical focusing ability forthe lens system.
 20. A miniature zoom lens system, comprising: a firstvarifocal lens positioned to receive incident light from an entrance tothe miniature lens system, the first varifocal lens comprising at leasttwo optical elements, each formed integrally with a frame; a first prismpositioned to receive light from the first varifocal lens through afirst face of the first prism and to bend the received light byapproximately 90 degrees before allowing the light to exit from a secondface of the first prism; a second varifocal lens positioned to receivethe light that exits the second face of the prism, the second varifocallens comprising at least two optical elements, each formed integrallywith a frame; at least one base lens positioned to receive the lightafter passing through the second varifocal lens; a second prismpositioned to receive the light that exits the at least one base lensthrough a first face of the second prism and to bend the light receivedby the second prism by approximately 90 degrees before allowing thelight to exit from a second face of the second prism; and at least oneactuator configured to connect to the frames of the optical elements tomove the optical elements of one or both of the first varifocal andsecond varifocal lenses in at least a direction perpendicular to anoptical axis of the system.